The subject matter disclosed herein relates to gas turbines and, more particularly, to inter-stage seals in gas turbines.
Turbine components are typically directly exposed to high temperature gases, and therefore require cooling to meet their useful life. For example, some of the compressor discharge air is diverted from the combustion process for cooling rotor components of the turbine.
Turbine buckets, blades and vanes typically include internal cooling channels therein which receive compressor discharge air or other cooling gases for cooling thereof during operation. In addition, turbine rotor disks which support the buckets are subject to significant thermal loads and thus also need to be cooled to increase their lifetimes.
The main flow path of the turbine is designed to confine combustion gases as they flow through the turbine. Turbine rotor structural components must be provided with cooling air independent of the main gas flow to prevent ingestion of the hot combustion gases therein during operation, and must be shielded from direct exposure to the hot flowpath gas.
Such confinement is accomplished by rotary seals positioned between the rotating turbine buckets to prevent ingestion or back flow of the hot air or gases into interior portions of the turbine rotor structure. Such rotary seals are insufficient to completely protect the interior components, such as the rotor structure, rotor and rotor disks, requiring the additional use of purge flows of cooling air into and through the rotor cavity. Such additional measures to protect the interior components increase the cost and complexity and hinder the performance of gas turbines.
Accordingly, there is a need for improved systems and methods for cooling turbine engines, that reduce rotor cooling air purge flow levels, reduce complexity and preserve or improve turbine performance.